In an Active Matrix Organic Light Emitting Diode (AMOLED) display panel, the emission brightness of an OLED (Organic Light Emitting Diode) is directly proportional to an amplitude of a driving current supplied thereto. A great driving current is required to realize an optimal display effect. A Low Temperature Poly-Silicon technique has become an optimal selection for the AMOLED display panel because it may provide a high mobility. However an inherent problem of shifts in threshold voltages Vth of thin film transistors existed in the Low Temperature Poly-Silicon technique may cause non-uniformity in currents output from respective pixel circuits, such that the display brightness is also non-uniform.
Therefore, how to improve the uniformity in the currents output from the respective pixel circuits is a technical problem needed to be settled urgently in the art.